setting up my shed

[cottontail]

I am new to rabbits and want to start a colony. I have a shed that is 15 x 15 I built a pen that is 15 x 7 what kind of material would I use to build the walls, wood or wire? right now it is just 4 large wire dog crates side by side. I have 3 does and one buck, two of the does are californian and one is New zealand red. the buck is also a new zealand red. the nzr is about to kindle any day now. I put the youngest doe with the male in the pen yesterday and the other two are still in their cages. When should I put the others in there? The other doe is about 1 week pregnant. none are related and are only about three months apart. oldest is 7 months youngest is 4 months. I am worried about fights. I am thinking of letting the nzr have her babies in the cage and when the kits are 2 weeks old building a 8 x 6 pen for her and her babies. would that be too much trauma for her to be moved?

What kind of material for the floor? I see wood shavings and hay. I have timmothy hay; is that ok for them for ground cover? How often should I clean it?